package com.hspedu.newData.dmsxl.树.二叉树的遍历.层序遍历迭代法.队列;

import com.hspedu.newData.dmsxl.ds.TreeNode;
import org.junit.Test;

import java.util.*;

/**
 * @Author: yh
 * @description: 
 * @CreateTime: 2025-04-23 
 * @Version: 1.0
 */

public class LC102二叉树的层序遍历 {

    List<List<Integer>> result = new ArrayList<>();

    public List<List<Integer>> levelOrder(TreeNode root) {
        if(root== null) return result;
        Queue<TreeNode> queue = new LinkedList<>();

        queue.offer(root);
        while(!queue.isEmpty()){
            List<Integer> list = new ArrayList<>();

            int len = queue.size();

            while(len > 0){
                TreeNode node = queue.poll();
                list.add(node.val);
                if (node.left != null) queue.offer(node.left);
                if (node.right != null) queue.offer(node.right);

                len --;
            }
            result.add(list);
        }

        return result;

    }


    @Test
    public void test() {
        // 测试代码

        TreeNode t7 = new TreeNode(7);
        TreeNode t6 = new TreeNode(6);
        TreeNode t5 = new TreeNode(5);
        TreeNode t4 = new TreeNode(4);
        TreeNode t3 = new TreeNode(3,t6,t7);
        TreeNode t2 = new TreeNode(2,t4,t5);
        TreeNode t1 = new TreeNode(1,t2,t3);

        levelOrder(t1);
        System.out.println("==========");

    }
}
